The invention relates to a method for reducing a pixel-based resolution through selectively combining selective primary pixel outputs to combined secondary pixel outputs in a multi-color pick-up element, as recited in the opening paragraph of Claim 1.
Prior art, in particular as relating to CCD technology, has produced two-dimensional pick-up array devices with the number of pixels already passing the 1M level. For use in producing still pictures, the image rate is relatively low, such as a few per second, and the image outputting has been found fast enough. For movie images however, the output image rate has become a bottleneck. On the one hand, picture resolution may be maintained at its maximum level through multiplication of circuitry elements, but this would make the device much too expensive. On the other hand, prior art has found that a certain image preprocessing operation will lower output speed requirements, while also, in many applications a reduced resolution is less critical.
In particular, U.S. Pat. No. 5,926,215 presents a clear and well-defined procedure, as follows: read out rows 1, 2, 3, dump #2, and combine rows 1 & 3; then, read out rows 4, 5, 6, dump 5, and combine rows 4 & 6, and so on. In this way, the overall number of rows is lowered by a factor of three (3). Note that the combined row pairs have identical color patterns in the Bayer scheme, which in various situations will solve the color mix-up problem. On the other hand, the complete dumping of one third of the rows, and the reconstruction of a new pattern over a scale that is three times as large as the original vertical scale will tend to spoil much detail in the picture. Finally, the prior art has been found to be not amenable to flexibility, in the sense that the resolution could be adjusted to needs, and/or to the nature of the scene as imaged.